<!DOCTYPE html>
<html>

	<head>
		<meta charset="UTF-8">
		<title></title>
	</head>

	<body>
		<button id="btn">点击</button>
		<script>
			var btn = document.getElementById("btn");
//			btn.addEventListener('click', fn1, false); //添加事件
			btn.addEventListener('click', fn2, false);
			btn.removeEventListener('click',fn,false);//删除事件

		var fn1=function(){
				var i=2;
				return i;
			}
		alert(fn1);
		

			function fn2() {
				alert("mm");
			}
		</script>
	</body>

</html>